Reactive oxygen species in rats with chronic post-ischemia pain.

BACKGROUND: An emerging theme in the study of the pathophysiology of persistent pain is the role of reactive oxygen species (ROS). In the present study, we examined the hypothesis that the exogenous supply of antioxidant drugs during peri-reperfusion would attenuate pain induced by ischemia/reperfusion (IR) injury. We investigated the analgesic effects of three antioxidants administered during peri-reperfusion using an animal model of complex regional pain syndrome-type I consisting of chronic post-ischemia pain (CPIP) of the hind paw. METHODS: Application of a tight-fitting tourniquet for a period of 3 h produced CPIP in male Sprague-Dawley rats. Low-dose allopurinol (4 mg/kg), high-dose allopurinol (40 mg/kg), superoxide dismutase (SOD, 4000 U/kg), N-nitro-L-arginine methyl ester (L-NAME, 10 mg/kg), or SOD (4000 U/kg)+L-NAME (10 mg/kg) was administered intraperitoneally just after tourniquet application and at 1 and 2 days after reperfusion for 3 days. The effects of antioxidants in rats were investigated using mechanical and cold stimuli. Each group consisted of seven rats. RESULTS: Allopurinol caused significant alleviation in mechanical and cold allodynia for a period of 4 weeks in rats with CPIP. Both SOD and L-NAME, which were used to investigate the roles of superoxide (O2(-)) and nitric oxide (NO) in pain, also attenuated neuropathic-like pain symptoms in rats for 4 weeks. CONCLUSIONS: Our findings suggest that O2(-) and NO mediate IR injury-induced chronic pain, and that ROS scavengers administered during the peri-reperfusion period have long-term analgesic effects.

A purified inactivated Japanese encephalitis virus vaccine made in Vero cells.

A second generation, purified, inactivated vaccine (PIV) against Japanese encephalitis (JE) virus was produced and tested in mice where it was found to be highly immunogenic and protective. The JE-PIV was made from an attenuated strain of JE virus propagated in certified Vero cells, purified, and inactivated with formalin. Its manufacture followed current GMP guidelines for the production of biologicals. The manufacturing process was efficient in generating a high yield of virus, essentially free of contaminating host cell proteins and nucleic acids. The PIV was formulated with aluminum hydroxide and administered to mice by subcutaneous inoculation. Vaccinated animals developed high-titered JE virus neutralizing antibodies in a dose dependent fashion after two injections. The vaccine protected mice against morbidity and mortality after challenge with live, virulent, JE virus. Compared with the existing licensed mouse brain-derived vaccine, JE-Vax, the Vero cell-derived JE-PIV was more immunogenic and as effective as preventing encephalitis in mice. The JE-PIV is currently being tested for safety and immunogenicity in volunteers.

Vitamin E improves microsomal phospholipase A2 activity and the arachidonic acid cascade in kidney of diabetic rats.

The purpose of the present study was to investigate the effects of vitamin E on microsomal phospholipase A2 activity and the arachidonic acid cascade in the kidneys of streptozotocin (STZ)-induced diabetic rats. Sprague-Dawley male rats weighing 100 +/- 10 g were randomly assigned to one normal and three STZ-induced diabetic groups. The diabetic groups were fed a vitamin E-free diet (the DM-0E group), 40 mg vitamin E/kg diet (the DM-40E group) or a 400 mg vitamin E/kg diet (the DM-400E group). The kidney vitamin E concentrations were 59 and 49% lower in the DM-0E and DM-40E groups, respectively, than in the normal group. The kidney thiobarbituric acid reactive substance concentrations in the DM-0E, DM-40E and DM-400E groups were 119, 84 and 33% greater, respectively, than that in the normal group. The concentration in the DM-400E group was 39% lower than that in the DM-0E group. The phospholipase A2 (PLA2) activity in the kidney microsomes of the DM-0E-40E and DM-400E groups were 88, 58 and 35% greater, respectively, than that in the normal group. The activity in the DM-400E group was 28% lower than that in the DM-0E group and 16% lower than that in the DM-40E group. The differences in the phospholipids in the kidney microsomes included reductions in the phosphatidylcholine and phosphatidylethanolamine compositions. Phosphatidylethanolamine hydrolysis in the kidney microsomes of the DM-0E and DM-40E groups were 84 and 64%, which did not differ from the DM-400E group. The formation of thromboxane A2 (TXA2) in the kidney microsomes was 137 and 70% greater in the DM-0E and DM-40E groups, respectively, than in the normal group. TXA2 formation did not differ between the DM-400E and normal groups. The formation of prostacyclin in the kidney microsomes was 60 and 44% lower in the DM-0E and DM-40E groups, respectively, than in the normal group, whereas the DM-400E group did not differ from that in the normal group. The ratio of prostacyclin to TXA2 was 82 and 65% lower than normal in the DM-0E and DM-40E groups, respectively. Kidney function appears to be improved by vitamin E supplementation due to its antithrombus action, which in turn controls the arachidonic acid cascade system.

Modified smear method for screening potential inhibitors of platelet aggregation from plant sources.

The smear method developed by Velaskar and Chitre was modified to allow the massive screening of plant extracts and/or fractions for platelet antiaggregating activity. Aspirin and papaverine, known inhibitors of platelet aggregation, were tested by the modified method and showed comparable results with previously reported data. Fifty-four fractions prepared from eighteen plant species were screened for their inhibitory effects on adenosine 5'-diphosphate, arachidonic acid, or collagen-induced rat platelet aggregation. The results suggest that plants could be a potential source of inhibitors of platelet aggregation.